Flexible basecoat/clearcoat coating compositions

ABSTRACT

This invention is directed to flexible basecoat/clearcoat coating systems which have excellent adherence to metal and plastic substrates and possess superior weathering properties. The clearcoat composition comprises hydroxy-containing urethane modified polyester, made by reacting a urethane modified diol with polyol and diacid component, crosslinkable with amine-aldehydes. The basecoat composition comprises hydroxy-containing urethane modified polyesters, made by reacting hydroxy functional polyester with diisocyanate, crosslinkable with amine-aldehyde and pigment. Optionally, either or both compositions may comprise a high molecular weight linear polyurethane.

Reference is made to concurrently filed and commonly assigned relatedU.S. application Ser. No. 555,463 entitled "Flexible Basecoat/TwoComponent Clearcoat Coating Compositions", abandoned in favor ofcontinuation-in-part application U.S. Ser. No. 615,700 filed May 29,1984, U.S. application Ser. No. 558,399 entitled "Flexible Two ComponentUrethane Coating Compositions", U.S. application Ser. No. 598,551entitled "Flexible Uni-Basecoat/Two Component Clearcoat CoatingCompositions", all to Kordomenos et al., and U.S. application Ser. No.553,322 entitled "Flexible Coating Compositions", to Alexander et al.

TECHNICAL FIELD

This invention relates to flexible basecoat/clearcoat coating systemswhich have excellent adherence to metal and plastic substrates andpossess superior weathering properties. Basecoat/clearcoat systemscomprise a finish of a clearcoat top layer in film adherence to abasecoat that is in adherence to a substrate. More particularly, theinvention relates to basecoat/clearcoat coating compositions whichcomprise hydroxy-containing urethane modified polyester, amine-aldehydecrosslinker, and, optionally, a high molecular weight linearpolyurethane. The hydroxy-containing urethane modified polyesters of thepigmented basecoat are made by reacting polyester polyol resins withisocyanate, while the novel hydroxy-containing urethane modifiedpolyesters of the clearcoat are made from urethane modified diolsreacted with polyol and diacid component.

BACKGROUND ART

Recently, there has been interest in the use of rubbery resilientmaterials for areas which are subject to mechanical shock such asautomobile bumpers, moldings and front ends. The use of such materialsaids in providing protection from permanent structural damage but, inorder to attain the desired appearance, a protective coating must haveunique properties, such as a high degree of extensibility, impactresistance, resistance to cracking under severe environmentalconditions, such as exposure to low temperature and low humidity.Conventional coatings, including those employed on rubber and similarextensible objects heretofore, do not have the required combination ofproperties. Generally compositions that are flexible enough to beapplied over both metal and plastic substrates have rather poorweatherability and overall durability.

U.S. Pat. No. 3,882,189 and U.S. Pat. No. 3,962,522 are exemplary ofnumerous patents which describe flexible coating compositions whereinthe resin comprises polyurethane modified polyesters formed by reactingpolyisocyanate with polyester polyols. These resins are cured with aminealdehyde crosslinkers. It is taught therein, that the presence of theurethane groups in the polymer significantly contributes to theflexibility as well as improved weathering properties, gloss, andabrasion resistance of the coating. However, while it is thus desirableto employ a substantial number of urethane groups in these resins, theamount which may be included in these types of resins is limited. Whenhydroxy polyester resin is reacted with polyisocyanate it has a tendencyto form a gelled mass and thus the amount of polyisocyanate that may beemployed must be restricted in order to avoid gelation. Still further,these urethane linkages are added in a latter modification of thepolyester polyol reaction product, rather than being incorporated intothe backbone of the resin.

DISCLOSURE OF THE INVENTION

This invention is directed to flexible basecoat/clearcoat coatingcompositions which are suitable for use over various substrates. Thecompositions may be used over rubbery, resilient materials as well asover metal. The basecoat/clearcoat coating composition of this inventionis characterized in that:

I. the clearcoat composition comprises:

(A) hydroxy-containing urethane modified polyester (i) having a numberaverage molecular weight (M_(n)) of between about 1000 and about 10,000,(ii) having a hydroxyl number of between about 30 and about 200, and(iii) containing between about 1 and about 10 urethane groups permolecule, and being made from reactants comprising:

(1) urethane modified diol made by reacting:

(a) diol, and

(b) diisocyanate,

wherein the diol and diisocyanate are reacted in a molar ratio of fromabout 4:1 to about 4:3;

(2) polyol comprising at least about 5 weight percent triol; and

(3) acid component selected from dicarboxylic acids and anhydridesthereof; and

(B) amine-aldehyde crosslinking agent; and

II. the basecoat composition comprises:

(A) hydroxyl-containing urethane modified polyester (i) having a numberaverage molecular weight (M_(n)) of between about 1000 and about 10,000,(ii) having a hydroxyl number of between about 50 and about 250, and(iii) containing between about 1 and about 7 urethane groups permolecule, and being made from reactants comprising:

(1) hydroxy functional polyester prepared from a mixture of (a)polyhydroxy materials comprising diols and triols with (b) acidcomponent selected from dicarboxylic acids and anhydrides thereof; and

(2) diisocyanate;

wherein in forming the hydroxyl functional polyester, the proportion ofreactants (a) and (b) are selected so that the OH/COOH ratio is fromabout 6:2 to about 6:5; and wherein in forming the modified polyester,the proportion of hydroxy functional polyester (1) and the diisocyanate(2) are selected so as to provide from about 4:1 to about 10:1hydroxyl/isocyanate groups;

(B) amine-aldehyde crosslinking agent; and

(C) pigment.

Preferably, the polyhydroxy materials (a) comprise the diols and triolsin a hydroxyl equivalent ratio of from about 4:1 to about 1:4, morepreferably this ratio is from about 3:1 to about 3:2.5.

The basecoat composition and the clearcoat composition may optionallyindividually comprise up to about 60 weight percent, based on the totalweight of (A) and (B) of each composition, of a linear polyurethanehaving a number average molecular weight of between about 15,000 andabout 40,000, preferably of between about 20,000 and about 30,000.

Advantageously, the flexible basecoat/clearcoat coating compositions ofthe invention of this application possess superior weathering propertiesas well as excellent adhesion to metal and plastic, thus making themwell suited for use as coatings on various car components. Mostparticularly, these improved weathering properties are a result of theclearcoat compositions of the basecoat/clearcoat coating composition ofthis application. In forming the hydroxy-containing urethane modifiedpolyester of the clearcoat, the urethane linkages are advantageouslyincorporated into the backbone of the modified polyester, since they areformed in an initial reaction of diisocyanate with the diol, rather thanbeing incorporated into the polyester in a later reaction step as isdone when forming prior art urethane polyester resins. It has now beenfound that the initial incorporation of the urethane linkage into thebackbone of the modified polyester allows the formation of more flexiblecoatings with improved weathering properties, particularly suitable toform automotive basecoat/clearcoat coatings.

Still further, the ability to use of the same coating compositions onmetal and plastic components in car production offers distinctcommercial advantages, particularly in terms of production efficiency.Additionally, because these coatings can be employed on metal as well asplastic components, the problem of color matching, which must beresolved when using a different coating on the metal and plastic, iseliminated.

BEST MODE FOR CARRYING OUT THE INVENTION

This invention is directed to flexible basecoat/clearcoat coatingcompositions which comprise hydroxy-containing urethane modifiedpolyester crosslinkable with amine-aldehyde crosslinking agent. Thehydroxy-containing urethane modified polyesters of the basecoat are madeby reacting polyester polyol resins with with isocyanate, while thehydroxy-containing urethane modified polyesters of the clearcoat aremade from urethane modified diols reacted with polyol and diacidcomponent. Either or both of the basecoat and clearcoat composition mayoptionally include a high molecular weight linear polyurethane. Thevarious components of the basecoat composition and the clearcoatcomposition will be discussed in detail.

The hydroxy-containing urethane modified polyester of the clearcoatcoating composition of this invention has a number average molecularweight (M_(n)) of between about 1000 and about 10,000, preferablybetween about 2000 and about 4000. This modified polyester has a hydroxynumber of between about 30 and about 200, preferably between about 50and about 120. It also contains between about 1 and about 10 urethanegroups per molecule. One of the reactants used to form thehydroxy-containing urethane modified clearcoat polyester is a urethanemodified diol which is made by reacting diol and diisocyanate. Informing this urethane modified diol, the diol and the diisocyanate arereacted in a molar ratio of from about 4:1 to about 4:3, preferably in amolar ratio of from about 2:0.8 to about 2:1.2, most preferably in abouta 2:1 molar ratio. The diols employed in making the urethane modifieddiol include, but are not limited to, alkylene glycols, such as butyleneglycol, neopentyl glycol, 1,5,pentene glycol,3-cyclohexene-1,1-dimethynol, and other glycols such as hydrogenatedbisphenol A, caprolactone diol (i.e., the reaction product ofcaprolactone and ethylene glycol), hydroxy alkylated bisphenols,polyether glycols, e.g., poly(oxytetramethylene) glycol, polyesterdiols, e.g.,2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, and thelike. Preferred diols are neopentyl glycol and2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxy-propionate, thelatter material being commercially available as Esterdiol 204 (atrademark of and available from Union Carbide Corp., New York, N.Y.).While a number of types of diols have been mentioned above as suitablefor use as the diol component in making the urethane modified diol ofthis invention, their disclosure is not meant to be limiting. A greatmany diols are known in the art. Selection of other diols which would besuitable for use in forming the urethane modified diol would be wellwithin the skill of those in the art. Mixtures of diols may also beemployed in making the urethane modified diol.

The diisocyanate employed in making the urethane modified diol may beessentially any diisocyanate. Many such organic diisocyanates are knownin the art. Suitable diisocyanates include hydrocarbon diisocyanate orsubstituted hydrocarbon diisocyanate, such as 1,6-hexamethylenediisocyanate, isophorone diisocyanate, p-phenylene diisocyanate,biphenyl diisocyanate, toluene diisocyanate, and3,3-dimethyl-4,4-biphenylene diisocyanate. While the diisocyanate may beany of a number of aliphatic, cycloaliphatic, and aromaticdiisocyanates, it is preferred that the diisocyanate be an aliphaticdiisocyanate, such as 4,4-dicyclohexylmethane-diisocyanate. As would beapparent to those skilled in the art, mixtures of various diisocyanatesmay also be employed at the diisocyanate component used in forming theurethane-modifying diol.

The polyol component used in forming the hydroxy-containing urethanemodified polyester of the clearcoat comprises at least about 5 weightpercent triol (based on the weight of the polyol component). Preferredtriols are conventional low molecular triols such as 1,2,6-hexene triol,1,1,1-trimethylol propane, pentaerythritol,3-(2-hydroxy-propoxy)-1,2-propanediol and polycaprolactone triols, whichare commercially available as, for example, PCP-301 (trademark, UnionCarbide Corp., New York, N.Y.). This polyol component may also comprise,in addition to the triols, other polyol materials such as diols ortetrols. Preferably, however, these other polyols, when employed,consist of diols. Examples of suitable diols which may be included inthe polyol component are those which have been disclosed above assuitable for forming the urethane modified diol of the clearcoat.Preferred diols for use in the polyol component are linear aliphatictype diols. While the polyol component may comprise materials such asdiols in addition to the triols, the polyol component may consistessentially of triols. By employing diols in the polyol component inaddition to the triols the flexibility of the coating composition isgenerally increased. Thus selection of the polyol component to be usedin forming the hydroxy-containing urethane modified polyester of theclearcoat will be dependent on the particular desired properties andapplication of the coating composition. When diols are employed in thepolyol component, the polyol preferably comprises from about 10 to about80 weight percent triols and from about 90 to about 20 weight percentdiols.

The acid component which is used to form the modified polyester of theclearcoat comprises aliphatic, aromatic, cycloaliphatic dicarboxylicacids or anhydrides thereof. Preferred dicarboxylic acids are the C₆-C₁₂ acids, which include adipic, azelaic, sebasic, or dodecanedicarboxylic acid, or cyclohexanedicarboxylic acid. More preferably, thedicarboxylic acids employed are aliphatic dicarboxylic acids, mostpreferably additionally being linear. Mixtures of suitable acids and/ortheir anhydrides may also be used as the acid component in thisinvention.

In forming the clearcoat coating compositions of this invention, thediol (a) and the diisocyanate (b) described above are combined andreacted, generally at an elevated temperature, so as to form theurethane modified diol. The ratio of the diol to diisocyanate (i.e., amolar excess of diol) has been chosen so that at the completion of thisreaction no free isocyanates are present, having been incorporated intoa hydroxy functional material. This urethane modified diol is thencombined and reacted with the polyol and acid components, generally inthe presence of a catalyst and at elevated temperature, so as to effectformation of a hydroxy-containing urethane modified polyester. Suitablecatalysts for the carboxy/hydroxy condensation reaction include suchcatalysts as tetraisopropyl titanate, strong acids such as p-toluenesulfonic acid, phosphoric acid, sulfuric acid and materials such as zincoxide, antimony oxide (Sb₂ O₃) and sodium acetate. Other catalysts willbe apparent to those skilled in the art.

The hydroxy-containing urethane modified polyester of the basecoatcoating composition has a number average molecular weight (M_(n)) ofbetween about 1,000 and about 10,000, preferably between about 2000 andabout 4000. This modified polyester has a hydroxy number of betweenabout 50 and about 250. It also contains between about 1 and about 7urethane groups per molecule. This modified polyester is made fromhydroxy functional polyester and diisocyanate reacted in suchproportions so as to provide from about 4 to about 10 hydroxyl groupsper isocyanate group. The hydroxy functional polyester is made from amixture of (a) polyhydroxy materials comprising diols and triols with(b) acid component selected from dicarboxylic acids and anhydridesthereof. The proportion of reactants (a) and (b) are selected so thatthe OH/COOH ratio is from about 6:2 to about 6:5. Preferably, thepolyhydroxy materials comprise diols and triols in a hydroxyl equivalentratio from about 4:1 to about 1:4, more preferably from about 3:1 toabout 3:2.5. By hydroxyl equivalent ratio is meant the ratio of thehydroxyl equivalents of the diol to the hydroxyl equivalents of thetriol.

The diols, triols, acid components and diisocyanates which are employedin forming the hydroxy-containing urethane modified polyester of thebasecoat may be selected from such materials described above for makingthe hydroxy-containing urethane modified polyester of the clearcoat. Informing the hydroxy-containing urethane modified polyester of thebasecoat, the polyhydroxy materials (i.e., diols, triols and optionallytetrols, etc.) and acid component reactants are combined and reacted,generally at elevated temperatures and in the presence of a catalyst, soas to effect formation of the hydroxy functional polyester. Catalystsfor the carboxyl/hydroxy condensation reaction are well known in theart. Exemplary of such carboxy/hydroxy catalysts are those which havebeen disclosed above for use in the clearcoat formulation. This hydroxyfunctional polyester is then modified by reaction with the diisocyanate,whereby urethane groups are incorporated into the polyester.

The reactions, whereby the hydroxy-containing urethane modifiedpolyester of the basecoat or clearcoat are formed, are generally carriedout in the presence of solvents commonly employed for coatingformulations such as toluene, xylene, methyl amyl ketone, etc.

Another essential component of the coating compositions (basecoat andclearcoat) of this invention is an amine-aldehyde crosslinking agent.Amine-aldehyde crosslinking agents suitable for crosslinking hydroxyfunctional bearing materials are well known in the art. Typically, thesecrosslinking materials are product of reactions of melamine, or ureawith formaldehyde and various alcohols containing up to and including 4carbon atoms. Preferably, the amine-aldehyde crosslinking agents usefulin this invention are amine-aldehyde resins such as the condensationproducts of formaldehyde with melamine, substituted melamine, urea,benzoguanamine or substituted benzoguanamine. Preferred members of thisclass are methylated melamine-formaldehyde resins such ashexamethoxymethylmelamine. The particularly preferred crosslinkers arethe high solids melamine resins which have substantially 100 percentnonvolatile content as measured by the foil method at 45° C. for 45minutes. For the purposes of the preferred composition of this inventionit should be recognized that it is important not to introduce extraneousdiluents that lower the final solids content of the coating. Othersuitable amine-aldehyde crosslinking agents will be apparent to oneskilled in the art. The amine-aldehyde materials function as acrosslinking agent in the compositions of the invention by reacting withthe hydroxy functionality of the hydroxy-containing urethane modifiedpolyester (A) and by reaction with the hydroxy functionality on thelinear polyurethane, if such materials are included in the compositions.The amine-aldehyde crosslinking agent is generally included in thecoating composition in an amount of between about 5 and about 60, morepreferably between about 20 and about 40 weight percent based on theweight of the hydroxy-containing urethane modified polyester present inthe composition. Selection of the particular amount of amine-aldehydecrosslinking agent to be employed in each composition is dependent onthe desired properties of the coating compositions as well as itsintended use as would be apparent to one skilled in the art. The amountsof crosslinking agent to be employed in the basecoat composition and inthe clearcoat composition are selected individually, i.e., the weightpercent amounts of crosslinker employed in the basecoat composition andin the clearcoat composition of a particular basecoat/clearcoat systemmay be different or be similar.

Particular preferred crosslinking agents are the amino crosslinkingagents sold by American Cyanamid Company, Wayne, N.J. under thetrademark "Cymel". In particular, Cymel 301, 303,325, 1130, 1156, whichare alkalated melamine aldehyde resins are useful in the compositions ofthis invention. The crosslinking reactions are catalytically acceleratedby acids. One such catalyst for example which may be so employed isp-toluene sulfonic acid which when employed, is generally added to thecomposition in about 0.5% by weight based on the total weight of theamine-aldehyde crosslinker and the hydroxy-containing urethane modifiedpolyester of the composition.

The basecoat coating composition of the invention also includespigments, as noted above. A wide variety of pigments are available andknown for use in coating compositions by those skilled in the art. Theamount of pigment in the basecoat coating compositions may vary.Selection of the optimal amount of pigment to be included in thebasecoat compositions would be dependent on, e.g., desired color, hidingrequirements of the coating, etc., and would be within the skill ofthose in the art.

OPTIONAL MATERIALS

Additional materials which may be employed in the coating compositionsof this invention include a high molecular weight linear polyurethanewhich has a number average molecular weight of between about 15,000 andabout 40,000, preferably between about 20,000 and about 30,000. It maybe made by reacting one of the above mentioned diisocyanates and diols,such as oligoester diol, polycaprolactone diol, polyoxypropylene diol,polyether diols, etc. Suitable high molecular weight linear polyurethanematerials are commercially available, for example, as Spenlite LO6-30S,(available from and a trademark of Spencer-Kellogg, Buffalo, N.Y.). Thehigh molecular weight linear polyurethane may be employed in thecompositions in amounts up to about 60 weight percent based on the totalweight of the hydroxy-containing urethane modified polyester andcrosslinking agent. When employed, it is preferred that they be includedin the composition in amounts of between about 10%-60%, more preferablyin amounts of about 30%-50% by weight as described. It has been foundthat by including these linear polyurethanes in the basecoat of thesebasecoat/clearcoat systems, the depth of color and metallic glamour ofthe system is improved. While this linear polyurethane, when employed,is generally preferably only included in the basecoat composition, itmay be employed in either or both coats and the amounts employed areindependently selected.

In addition to the above discussed components, other materials may beincluded in the coating compositions of this invention. These includematerials such as catalysts, antioxidants, U.V. absorbers, solvents,surface modifiers and whitening agents. Solvents used in the coatingcomposition of this invention are those which are commonly used, e.g.,to facilitate spray application at high solids content and includetoluene, xylene, methylethyl ketone, acetone, 2-ethoxy-1-ethanol,diacetone alcohol, tetrahydrofuran, ethyl acetate, dimethylsuccinate,dimethylglutarate, dimethyladipate or mixtures thereof. The solvent inwhich the hydroxy-containing urethane modified polyester is prepared maybe employed as a solvent for the composition thus eliminating the needfor drying the resin after preparation, if such is desired.

Typical of the ultraviolet light stabilizers that are useful in thisinvention are benzophenones such as dodecyl oxibenzophenone,2,4-dihydroxybenzophenone, hydroxybenzophenones containing sulfonicgroups, 2,4-dihydroxy-3',5'-ditertiarybutylbenzophenone,2,2',4'-trihydroxybenzophenone esters of dicarboxylic acids,2-hydroxy-4-acryloxyethoxybenzophenone, aliphatic monoesters of2,2',4-trihydroxy-4'-alkoxybenzophenone;2-hydroxy-4-methoxy-2-carboxybenzophenone; triazoles such as2-phenyl-4-(2'4'-dihydroxybenzoyl)triazoles substituted benzotriazolessuch as hydroxy-phenyltriazoles such as2-(2'-hydroxy-5'-methylphenyl)benzotriazole,2-(2'-hydroxyphenyl)benzotriazole,2-(2'-hydroxy-5'-octylphenyl)naphthiotriazole.

Another type of ultraviolet light stabilizer and one that isparticularly preferred for use in the coatings of this invention is thattaught in concurrently filed U.S. application Ser. No. 553,321, now U.S.Pat. No. 4,480,084 entitled "Polymeric Light Stabilizers" to Kordomenoset al. These stabilizers contain the sterically hinderedpolyalkylpiperidine radical and at least two primary hydroxyl groupsavailable for crosslinking with the amine-aldehyde component of thecoating composition.

Typical of the antioxidants which may be employed in the coatingcomposition are tetrakis alkylene(di-alkyl hydroxy aryl)alkyl esteralkanes such as tetrakis methylene3-(3',5'-dibutyl-4'hydroxyphenyl)proprionate methane, reaction productof p-amino diphenylamine and glycidyl methacrylate, reaction product ofn-hexyl-N'-phenyl-p-phenylene diamine and glycidyl methacrylate,pentaerythritol tetrakis(thioglycolate), trimethylol propanetris(thioglycolate), trimethylol ethane tris(thioglycoate),N-(4-anilinophenyl)acrylamide, N-(4-anilinophenyl)maleamic acid,N-(4-anilinophenyl)maleimide, alkylhydroxyphenyl groups bonded throughcarboalkoxy linkages to nitrogen atom of a heterocyclic nucleuscontaining an imidodicarbonyl group or an inidodithiocarbonyl group,3,3-ditertbutyl-4-hydroxy cinnamonitrile, ethyl3,5-diterthexyl-4-hydroxy cinnamate, substituted benzyl esters ofbeta-substituted hydroxyphenyl propionic acids, bis-(hydroxyphenylalkylene)alkyl isocyanurate compounds, tetrakis hydroxy benzylphosphonium halides alone or in combination with adialkylthiodialkanoate, thiodimethylidyne tetrakisphenols alone or incombination with a dialkyl thiodialkanoate or phosphite or phosphonate,dihydrocarbyl-hydroxy phenyl aryl or alkyl phosphonites or phosphonatesor phosphates or phosphites or phosphinates or phosphinites orphosphorothionates or phosphinothionates, diphenylbis(3,5-ditertbutyl-4-hydroxyphenoxy)silane,hydrocarbyl-hydroxyphenyl-dihydrocarbyldithio-carbamates such as3,5-ditertbutyl-4-hydroxyphenyl dimethyldithio carbamate and aminobenzyl thioether.

In one preferred embodiment of basecoat/clearcoat compositions, thebasecoat would preferably contain only a benzotriazole U.V. stabilizersuch as Tinuvin 328 (a trademark of and commercially available fromCiba-Geigy, Ardsley, N.Y.) and the clearcoat would contain abenzotriazole U.V. stabilizer, e.g., Tinuvin 328, the polymeric hinderedamine light stabilizer of the aforementioned concurrently filedapplication to Kordomenos et al, and an antioxidant, e.g., Irganox-1010(available from and a trademark of Ciba-Geigy). While preferredcombinations of stabilizers and antioxidants have been described, theseteachings are not meant to be limiting. Selection of the optimal type ofstabilizer and antioxidant which may be employed would be within theskill of one in the art.

Surface modifiers or wetting agents are common additives for liquidpaint compositions. Exact mode of operation of these surface modifiersis not known but it is thought that their presence contributes to betteradhesion of coating compositions to the surface being coated and helpsformation of thin coatings, particularly on metal surfaces. The choiceof surface modifiers or wetting agents is dependent upon the type ofsurface to be coated. Selection of appropriate surface modifiers will bewell within the skill of the artesian. Typical of these surfacemodifiers are polybutyl acrylate and a wide variety of silicon wettingagents which are commercially available.

For many applications of the coating compositions of the invention,particularly high solids compositions, it may be desirable to employflow control additives to provide sag free coatings. Among numerous suchmaterials are NAD's such as described by Porter (S. Porter, Jr., and B.N. McBane, U.S. Pat. No. 4,025,474, May 24, 1977). These particledispersions may be included generally in an amount up to 15% by weightof the total composition. Other types of NAD's such as described by D.L. Maker and S. C. Peng (U.S. Pat. No. 3,814,721, June 4, 1974) or by S.K. Horvath (U.S. Ser. No. 292,853, filed Aug. 14, 1981, now U.S. Pat.No. 4,415,681) also may be included in the coating compositions.

The coating composition can be applied by conventional methods known tothose in the art. These methods include roll coating, spray coating,dipping or brushing and of course the particular application techniquechosen with the particular substrate to be coating and the environmentin which coating operation takes place.

Particular preferred techniques for applying these coating compositions,particularly when applying the same to automobiles, is spray coatingthrough the nozzle of the spray gun.

INDUSTRIAL APPLICABILITY

It will be apparent from the foregoing that this invention hasindustrial applicability to automotive applications and provides aflexible durable coating for metal and plastic substrates.

The invention will be further understood by referring to the followingdetailed examples. It should be under stood that the specific examplesare presented by way of illustration and not by way of limitation.Unless otherwise specified, all references to "parts" is intended tomean parts by weight.

EXAMPLE I

In a suitable reactor 720 gms of Esterdiol-204 (trademark of UnionCarbide), 216 gms of trimethylol propane, 2 gms of dibutyl tin oxide and504 gms of adipic acid were charged. The temperature was raised up to149° C. and kept at this temperature until the acid number dropped to10. At this point 150 gms of xylene were added and the temperature wasraised to 177° C. and kept there until the acid number was 2. The batchwas then cooled down to 93° C. and 255 gms of Desmodur W (diisocyanate,trademark, Mobay Chemical Co., Pittsburgh, PA) were added in a period ofone hour. After the end of the addition, the mixture was kept at 93° C.until there was no NCO group was observed in an infrared spectrum. Thebatch was then thinned to 70% NV with methyl amyl ketone and had aviscosity of Z₁.

EXAMPLE II

In a suitable reactor 1020 gms of Esterdiol-204 (trademark, UnionCarbide), 224 gms of trimethylol propane and 724 of DMCD (dimethyl1,4-cyclohexanedicarboxylate available from Eastman Chemical ProductsInc.) were charged. The mixture was heated to 193° C. and kept at thistemperature until 210 gms of methanol were stripped out. At this point,the mixture was cooled down to 149° C. and 165 gms of isophthalic acidand 1.5 gms of dibutyl tin oxide were added. The temperature was raisedto 232° C. and water was stripped out until the acid number dropped to10.1. The reaction mixture was cooled down to 149° C. and 480 parts ofxylene were added. When the batch temperature dropped to 93° C., 320 gmsof isophoroic diisocyanate were added in a period of one hour. After theend of the addition, the mixture was kept at 93° C. until there was noNCO group was observed in an infrared spectrum. The batch was thenthinned to 71.3% NV with methyl amyl ketone and had a viscosity of X+.

EXAMPLE III

In a suitable reactor 562 gms of Esterdiol-204 (trademark of UnionCarbide) and 360 gms of xylene were charged. The mixture was brought toreflux (149° C.) and any water present was stripped out. The temperaturewas lowered to 93° C. and 360 gms of Desmodur W (trademark of MobayChemical Co.) was added dropwise in a period of one hour. After the endof the addition, the mixture was postreacted at 93° C. until no NCOgroup was observed in an IR spectrum. At this point, 240 gms of PCP-0301(polycaprolactone triol, trademark of Union Carbide, New York, N.Y.) 263gms of adipic acid, 3 gms of dibutyl tin oxide, and 215 gms of xylenewere added. The mixture was heated up to 204° C. and water was distilledoff until the acid number dropped below 10. The batch was then thinnedwith 480 parts of methyl amyl ketone. The final product had Z₃ viscosityat 70.8% NV and acid number 1.2.

EXAMPLE III'

In a suitable reactor 562 gms of Esterdiol-204 (trademark of UnionCarbide) and 360 gms of xylene were charged. The mixture was brought toreflux (149°) and any water present was stripped out. The temperaturewas lowered to 93° C. and 360 gms of Desmodur W (trademark of MobayChemical Co.) was added dropwise in a period of one hour. After the endof the addition, the mixture was postreacted at 93° C. until no NCOgroup was observed in an IR spectrum. At this point, 240 gms of PCP-0301(polycaprolactone triol, trademark of Union Carbide, New York, N.Y.) 131gms of adipic acid and 133 gms of phthalic anhydride, 3 gms of dibutyltin oxide, and 215 gms of xylene were added. The mixture was heated upto 204° C. and water was distilled off until the acid number droppedbelow 10. The batch was then thinned with 480 parts of methyl amylketone. The final product had Z₅ viscosity at 70.1% NV and acid number3.

EXAMPLE IV

In a suitable reactor 314 gms of Esterdiol-204 (trademark of UnionCarbide) and 175 gms of xylene were charged. The mixture was brought toreflux (149° C.) and any water present was stripped out. The temperaturewas lowered to 93° C. and 202 gms of Desmodur-W (trademark, MobayChemical Co.) were added dropwise in a period of one hour. After the endof the addition, the mixture was postreacted at 93° C. until no NCOgroup was observed in an IR spectrum. At this point, 359 gms ofEsterdiol-204 (trademark, Union Carbide), 441 parts of PCP-0301(polycaprolactone triol, trademark, Union Carbide), 482 gms of adipicacid, 250 gms of xylene, and 3 gms of dibutyl tin oxide were charged.The mixture was heated up to 204° C. and water was distilled off untilthe acid number dropped below 10. The batch was then thinned with 478gms of methyl amyl ketone. The final product had a viscosity of X1/2 at70.1% NV and 0.9 acid number.

EXAMPLE V

In a suitable reactor 562 gms of Esterdiol-204 (trademark of UnionCarbide) and 360 gms of xylene were charged. The mixture was brought toreflux (149° C.) and any water present was stripped out. The temperaturewas lowered to 93° C. and 300 gms of isophorone diisocyanate was addeddropwise in a period of one hour. After the end of the addition, themixture was postreacted at 93° C. until no NCO group was observed in anIR spectrum. At this point, 240 gms of PCP-0301 (polycaprolactone triol,trademark of Union Carbide) 263 gms of adipic acid, 3 gms of dibutyl tinoxide, and 215 gms of xylene were added. The mixture was heated up to204° C. and water and xylene was distilled off until the acid numberdropped below 10. The batch was then thinned with 480 parts of methylamyl ketone. The final product had Y viscosity at 72. % NV and acidnumber 7.0.

EXAMPLE VI

In a suitable reactor 286 gms of neopentyl glycol and 360 gms of xylenewere charged. The temperature was raised to 93° C. and 360 gms ofDesmodur W (trademark of Mobay Chemical Co.) was added dropwise in aperiod of one hour. After the end of the addition, the mixture waspostreacted at 93° C. until no NCO group was observed in an IR spectrum.At this point, 240 gms of PCP-0301 (polycaprolactone triol, trademark ofUnion Carbide) 263 gms of adipic acid, 3 gms of dibutyl tin oxide, and215 gms of xylene were added. The mixture was heated up to 204° C. andwater and xylene was distilled off until the acid number dropped below10. The batch was then thinned with 480 parts of methyl amyl ketone. Thefinal product had Z₄ viscosity at 71.7% NV and acid number 0.8.

EXAMPLE VII

In a suitable reactor 281 gms of Esterdiol-204, 728 gms of PCP-0200(polycaprolactone diol, trademark of Union Carbide) and 360 gms ofxylene were charged. The mixture was brought to reflux (149° C.) and anywater present was stripped out. The temperature was lowered at 93° C.and 360 gms of Desmodur W (trademark of Mobay Chemical Co.) was addeddropwise in a period of one hour. After the end of the addition, themixture was postreacted at 93° C. until no NCO group was observed in anIR spectrum. At this point, 108 gms of trimethylol propane, 263 gms ofadipic acid, 3 gms of dibutyl tin oxide, and 200 gms of xylene wereadded. The mixture was heated up to 204° C. and water and xylene wasdistilled off until the acid number dropped below 10. The batch was thenthinned with 400 parts of methyl amyl ketone. The final product had Z₁viscosity at 72.7% NV and acid number 2.0.

EXAMPLE VIII

In a suitable reactor 562 gms of Esterdiol-204 (trademark of UnionCarbide) and 360 gms of xylene were charged. The mixture was brought toreflux (149° C.) and any water present was stripped out. The temperaturewas lowered to 93° C. and 360 gms of Desmodur W (trademark of MobayChemical Co.) was added dropwise in a period of one hour. After the endof the addition, the mixture was postreacted at 93° C. until no NCOgroup was observed in an IR spectrum. At this point, 108 gms oftrimethylol propane, 100 gms of dimer acid (Empol 1016, Emery, IND.), 3gms of dibutyl tin oxide, and 200 gms of xylene were added. The mixturewas heated up to 204° C. and water and xylene was distilled off untilthe acid number dropped below 10. The batch was then thinned with 400parts of methyl amyl ketone. The final product had X+ viscosity at 69.2NV and acid number 2.9.

EXAMPLE IX

In a suitable reactor 753 gms of Esterdiol-204 (trademark of UnionCarbide) and 360 gms of xylene were charged. The mixture was brought toreflux (149° C.) and any water present was stripped out. The temperaturewas lowered to 93° C. and 360 gms of Desmodur W (trademark of MobayChemical Co.) was added dropwise in a period of one hour. After the endof the addition, the mixture was postreacted at 93° C. until no NCOgroup was observed in an IR spectrum. At this point, 474 gms of PCP-0301(polycaprolactone triol, trademark of Union Carbide), 263 gms of adipicacid, 402 gms of dodeconoic acid, 4 gms of dibutyl tin oxide, and 200gms of xylene were added. The mixture was heated up to 204° C. and waterand xylene was distilled off until the acid number dropped below 10. Thebatch was then thinned with 480 parts of methyl amyl ketone. The finalproduct had Z₁ + viscosity at 70.0% NV and acid number 5.2.

EXAMPLE X

In a suitable reactor 136 gms of propylene glycol, 172 gms of adipicacid and 66.4 gms of toluene were added. The mixture was heated up toreflux and 42.6 gms of water were stripped. At this point 321 gms ofoligoester (made according to Example I of U.S. Pat. No. 4,322,508 toPeng et al.), 250 gms of toluene, 10 gms of dibutyl tin dilaurate wereadded. In a period of 3 hours, 396 parts of Desmodur W (trademark, MobayChemical Co.) were added. During the addition, the temperature wasallowed to rise from 116° C. to 143° C. The mixture was kept at thistemperature until no NCO group were observed in an IR spectrum. Thebatch was thinned with 860 gms of toluene and 1,260 gms isopropanol. Thefinal product had a W viscosity at 33.1% NV.

EXAMPLES XI-XIII

Flexible basecoat compositions were formulated according to thefollowing table:

    ______________________________________                                                    Example                                                           Compositions  XI         XII     XIII                                         ______________________________________                                        Resin of Example I                                                                          50                                                              Resin of Example II      50      50                                           Resin of Example X               100                                          Spenlite L06-30S.sup.1                                                                      100        100                                                  Cymel 1130.sup.2                                                                            46         46      46                                           Tinuvin-328   3.6        3.6     3.6                                          PTSA (40%)    1.5        1.5     1.5                                          5000-AR.sup.3 50         50      50                                           Xylene        75         75      75                                           Isopropyl Alcohol                                                                           75         75      75                                           Surfynol-104.sup.4                                                                          6          6       6                                            Methyl amyl ketone                                                            ______________________________________                                         The above basecoats were reduced to 20 sec. at #4 Ford Cup with methyl        amyl ketone before spraying.                                                  .sup.1 Trademark, SpencerKellogg, Buffalo, N.Y.                               .sup.2 Trademark, American Cyanamid Co., Wayne, N.J.                          .sup.3 Aluminum Paste, purchased Silberline, Lansford, PA.                    .sup.4 Trademark, Air Products and Chemicals, Inc., Allentown, Pa.,           (Surfactant, 2,4,7,9tetramethyl-5-decyn-4,7-diol)                        

    __________________________________________________________________________    Clearcoat Compositions                                                                    Example                                                           Composition XIV XV  XVI XVII                                                                              XVIII                                                                             XIX XX  XX'                                   __________________________________________________________________________    Resin of Example III                                                                      414                                                               Resin of Example III'                   414                                   Resin of Example IV                                                                           250                                                           Resin of Example V  398                                                       Resin of Example VI     400                                                   Resin of Example VII        394                                               Resin of Example VIII           414                                           Resin of Example IX                 224                                       Cymel 1130.sup.1                                                                          95  58  95.6                                                                              95  95  95  127 95                                    Tinuvin-328.sup.2                                                                         5.8 5.0 6   6   6   6   5.3 5.8                                   Polymeric Light                                                                           8.3 5.0 8   8   8   8   7.6 8.3                                   Stabilizer                                                                    2-ethyl hexanol                                                                           12.5                                                                              7.6 12.5                                                                              12.5                                                                              12.5                                                                              12.5                                                                              11  12.5                                  Methanol    4.3 26.3                                                                              41  43  43  43  40  4.3                                   Methyl amyl ketone                                                                        131 80  304 304 304 304 60  131                                   PTSA (40%)  8.3 3.2 5.3 5.3 5.3 5.3 7.1 8.3                                   Irganox 1010.sup.4                                                                        0.78                                                                              0.47                                                                              0.78                                                                              0.78                                                                              0.78                                                                              0.78    0.78                                  __________________________________________________________________________     The above compositions were reduced to 30 sec. viscosity at #4 Ford Cup       with methyl ethyl ketone.                                                     .sup.1 Trademark, American Cyanamid Co.                                       .sup.2 Trademark, CibaGeigy                                                   .sup.3 Stabilizer made according to Example I of U.S. application S.N. to     Kordomenos et al                                                              .sup.4 Trademark, CibaGeigy, (Antioxidant)                               

    __________________________________________________________________________    Examples XXI-XXX                                                              The following basecoat/clearcoat combinations were sprayed over metal and     plastic substrates and cured                                                  at 121° C. for 30 minutes.                                             Coating      Example                                                          Composition  XXI XXII                                                                              XXIII                                                                             XXIV                                                                              XXV XXVI                                                                              XXVII                                                                             XXVIII                                                                             XXIX                                                                              XXX                         __________________________________________________________________________    Basecoat of Example                                                                        XI  XII XIII                                                                              XI  XI  XI  XI  XI   XI  XI                          Clearcoat of Example                                                                       XIV XIV XIV XV  XVI XVII                                                                              XVIII                                                                             XIX  XX  XXI                         % elongation 100 60  85  60  85  100 75  100  95  50                          MEK resistance (100 rubs)                                                                  Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Good Excell                                                                            Excell                      QUV (1000 hrs.)                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                            Excell                                                                             Excell                                                                            Excell                      __________________________________________________________________________

We claim:
 1. A flexible basecoat/clearcoat coating composition, usefulas automotive finish coats on metal and plastic substrates, which ischaracterized in that:I. The clearcoat composition comprises:(A)hydroxy-containing urethane modified polyester (i) having a numberaverage molecular weight (M_(n)) of between about 1000 and about 10,000,(ii) having a hydroxyl number of between about 30 and about 200, and(iii) containing between about 1 and about 10 urethane groups permolecule, and being made from reactants comprising:(1) urethane modifieddiol made by reacting:(a) diol; and (b) diisocyanate, wherein said dioland said diisocyanate are reacted in a molar ratio of from about 4:1 toabout 4:3; (2) polyol comprising at least about 5 weight percent triol;and (3) acid component selected from dicarboxylic acids and anhydridesthereof; (B) amine-aldehyde crosslinking agent; and II. the basecoatcomposition comprises:(A) hydroxy-containing urethane modified polyester(i) having a number average molecular weight (M_(n)) of between about1000 and about 10,000, (ii) having a hydroxyl number of between about 50and about 250, and (iii) containing between about 1 and about 7 urethanegroups per molecule, and being made from reactants comprising:(1)hydroxy functional polyester prepared from a mixture of (a) polyhydroxymaterials comprising diols and triols and (b) acid component selectedfrom dicarboxylic acids and anhydrides thereof; and (2) diisocyanate;wherein in forming the hydroxy functional polyester, the proportion ofreactants (a) and (b) are selected so that the OH/COOH ratio is from 6:2to 6:5; and wherein in forming the modified polyester the proportion ofhydroxy functional polyester (1) and the diisocyanate (2) are selectedso as to provide from 4:1 to 10:1 hydroxyl/isocyanate groups; and (B)amine-aldehyde crosslinking agent; and (C) pigment; andwherein either orboth of said basecoat composition and said clearcoat compositionindividually comprises 0-60 weight percent, based on the total weight of(A) and (B) of each said composition, of a linear polyurethane having anumber average molecular weight of between about 15,000 and about40,000.
 2. A flexible basecoat/clearcoat coating composition accordingto claim 1, wherein said hydroxy-containing urethane modified polyesterof said clearcoat composition has a number average molecular weight(M_(n)) of between about 2000 and about
 4000. 3. A flexiblebasecoat/clearcoat coating composition according to claim 1, whereinsaid hydroxy-containing urethane modified polyester of said clearcoatcomposition has a hydroxyl number of between about 50 and about
 120. 4.A flexible basecoat/clearcoat coating composition according to claim 1,wherein in forming said urethane modified diol of said clearcoatcomposition said diol (a) and said diisocyanate (b) are reacted in amolar ratio of from about 2:0.8 to about 2:1.2.
 5. A flexiblebasecoat/clearcoat coating composition according to claim 1, whereinsaid polyol of said clearcoat composition further comprises diol.
 6. Aflexible basecoat/clearcoat coating composition according to claim 5,wherein said polyol of said clearcoat comprises about 10-80 weightpercent triol and about 90-20 weight percent diol.
 7. A flexiblebasecoat/clearcoat coating composition according to claim 1, whereinsaid dicarboxylic acids of said clearcoat composition comprise C₆ -C₁₂aliphatic dicarboxylic acids.
 8. A flexible basecoat/clearcoat coatingcomposition according to claim 1, wherein said amine-aldehydecrosslinking agent of said clearcoat composition is employed in anamount of from about 5 to about 60 weight percent based on the weight ofsaid hydroxy-containing modified polyester present in said clearcoatcomposition.
 9. A flexible basecoat/clearcoat composition according toclaim 1, wherein said hydroxy-containing urethane modified polyester ofsaid basecoat composition has a number average molecular weight (M_(n))of between about 2000 and about
 4000. 10. A flexible basecoat/clearcoatcoating composition according to claim 1, wherein saidhydroxy-containing urethane modified polyester of said basecoatcomposition has a hydroxyl number of between about 50 and about
 250. 11.A flexible basecoat/clearcoat coating composition according to claim 1,wherein said polyhydroxy materials (a) comprise said diols and saidtriols in a hydroxyl equivalent ratio of from about 4:1 to about 1:4.12. A flexible basecoat/clearcoat coating composition according to claim10, wherein said polyhydroxy materials (a) comprise said diols and saidtriols in a hydroxyl equivalent ratio of from about 3:1 to about 3:2.5.13. A flexible basecoat/clearcoat coating composition according to claim1, wherein said polyhydroxy materials employed in basecoat compositionpreparation comprise diols which are linear, aliphatic diols.
 14. Aflexible basecoat/clearcoat coating composition according to claim 1,wherein said dicarboxylic acids employed in basecoat compositionpreparation are C₆ -C₁₂ aliphatic dicarboxylic acid.
 15. A flexiblebasecoat/clearcoat coating composition according to claim 1, whereinsaid amine-aldehyde crosslinking agent of said basecoat composition isemployed in an amount of from about 5 to about 60 weight percent basedon the weight of said hydroxy-containing urethane modified polyesterpresent in said basecoat composition.